1. Field of the Invention
The present invention relates generally to agricultural equipment and more specifically to automatic bale wagons.
2. Description of the Prior Art
With the trend in farming practices towards increased mechanization, the automatic bale wagon, such as the type illustrated in U.S. Pat. No. 3,706,389, has been gaining acceptance as an essential farm implement. In these bale wagons, a pick-up mechanism lifts bales from the ground and loads them onto a first or receiving table, which sequentially moves two or more bales in end-to-end relationship onto a second or transfer table upon which a tier of bales is accumulated comprising a plurality of rows of bales (e.g. 4 rows). When a full complement of bales for a tier has been loaded upon the second table, the latter is pivoted from an almost horizontal position, about a transverse pivot axis, to a substantially vertical position to dispose the tier of bales either against a rolling rack upon a load bed of the wagon or against the forward face of a previously deposited tier of bales on the load bed. The load bed is positioned rearwardly of the second or transfer table, extends in a generally fore-and-aft direction and has its loading end facing in a forward direction. The transfer or second table with the tier of bales thereon pushes the rolling rack, together with any partially formed stack of bales, towards the rear of the wagon over the width of one bale so that a further tier can be transferred from the second table to the forward end of the load bed.
After accumulating successive bale tiers on the load bed to form a complete bale stack thereon, the stack may be transported to a desired location for discharge from the wagon in a composite stack. However, bale wagons have been evolved which can unload a stack one bale at a time. In this latter development, when bales are unloaded one by one, the second transfer table is placed in an inclined (45.degree.) position and the load on the load bed is caused to move in a forward direction step by step in a manner so that the forwardmost tier falls back onto the inclined transfer table. Unloading means on the transfer table unload the bales one by one in a sideways direction.
All operations of the various receiving and transfer tables, rolling rack, and the final unloading of the load bed are accomplished by hydraulic means and associated fluid circuits and control valves which are operated by appropriate cams, trip members and other means such as described in detail in the aforementioned patent specification.
Bale wagons of the types hereinbefore described are satisfactory when operating in generally flat fields. However, when using these bale wagons in hilly conditions, certain problems are encountered. One problem occurs when operating the bale wagon on a downward incline. It should be noted here that the front tier of bales on the load bed is held only by means engaging the uppermost bales, inter-bale friction being relied on to retain the intermediate bales and friction between the lowermost bales and the load bed being relied on to retain the lowermost bales. The upper bales may be contacted from above and on their upper surface by resiliently-loaded bale fingers tending to prevent the tier from falling back on the transfer table. It has been found in practice that the intermediate rows of bales occasionally slip in a forward direction, especially when the machine is operated on a downward incline, with the result that the front tier either adopts a curved profile or the tier actually falls from the load bed.
Should the front tier of bales fall from the load bed, the automatic operation of the wagon is disrupted and any bales falling on the transfer table have to be removed, or rearranged if in fact they can be accommodated thereon and the remaining bales of the now partial front tier have to be removed manually. If the front tier does not integrate but adopts a curved profile, subsequent tiers are likely to adopt a similar profile with the result that an unstable stack is formed.
One solution that has been attempted involves leaving the transfer table in the upper position after completing the loading of bales and whilst the wagon is driven to the desired discharge location. This, however, solves only part of the problem since it is necessary to keep the transfer table in its generally horizontal position during the appropriate part of the loading operation and the discussed problems can arise at this time. When unloading the wagon one bale at a time, the bale retainer fingers holding the top bales of a tier must be retracted so that the load can be moved in a forward direction. This means that during unloading even the top bales are no longer positively held in position which increases the risk of the front tier falling (partially or completely) onto the transfer table prematurely, especially since the wagon undergoes considerable vibration when a tier is moved intentionally from the load bed to the transfer table and the vibration can disturb the new front tier. The foregoing problem is aggravated when bales are stacked on their edge on the load bed rather than flat. Usually bales are 14 inches (35 cms) or 16 inches (40 cms) high, 18 inches (45 cms) wide and about 40 inches (90 cms) long. Twine is wrapped around each bale lengthwise and around the 18 inch edges. Stacking bales flat means that the bales are stacked with the 18 inch edges parallel to the load floor, whilst stacking bales on edge means that the 18 inch edges extend perpendicular to the load floor. Bales tend better to resist deformation when stacked flat rather than when stacked on their edges. Nevertheless, it is preferred to stack bales on their edges on the load bed since more bales can be accommodated on a bale wagon of given length and width. For example, it is possible to load sixteen tiers of eight 14 inch by 18 inch bales on a load bed of given length and width provided the bales are arranged on their edge. If however, the bales are stacked flat the same load bed can only hold twelve tiers. When each tier comprises four rows of two bales, this means 128 bales in the first situation against only 96 bales in the second situation. This also means, of course, that the height of the stack when on the load bed varies accordingly. Also the fore-and-aft dimension of the second or transfer table has to be somewhat larger in the former situation than in the latter situation. Now, given the situation where bales are stacked on their edge of the load bed, the stability of the four bale high stack, and especially of the front tier of the stack, is inferior for several reasons, namely (a) increased height of the tiers and correspondingly increased distance between the load bed and the bale retainer fingers, (b) decreased surface area upon which the bales rest, (c) reduced resistance of the bales against deformation--i.e. the bales are more flexible and subject to compression when stacked on their edges. Also, with an increased capacity of the load bed, a higher force has to be exerted by the second or transfer table on the bale stack already on the load bed to shift the latter further rearwardly so as to be able to deposit a further tier thereon. This is particularly true when the load bed is almost completely loaded and the result is that the bales, especially those of the last few tiers loaded on the load bed, are compressed substantially. When the transfer table is subsequently returned to its receiving position, these compressed bales, especially the middle ones of the tier, tend to revert to their original size by expanding in a forward direction and hence giving the tier a curved profile with the attendant problems already discussed.